


The Properties of a Binary System

by CaitlinFairchild



Series: Lessons in Astronomy [2]
Category: Sherlock (TV)
Genre: Accidental Voyeurism, Angst, Drug Addiction, M/M, Masturbation, No actual Holmescest, Pining, Post S3, Sibling Incest, Unrequited Love
Language: English
Status: Completed
Published: 2014-03-09
Updated: 2014-03-09
Packaged: 2018-01-15 02:52:43
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 8,826
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1288501
Author URL: https://archiveofourown.org/users/CaitlinFairchild/pseuds/CaitlinFairchild
Summary: <blockquote class="userstuff">
              <p>Despite being the entirety of the British Government, Mycroft always keeps his schedule open on January 6. Just in case.</p><p>This year his phone rings. It’s Sherlock’s fortieth, and Mycroft goes to Baker Street and eats a piece of cake just to give Sherlock some ammunition, something to tease and insult him over. Something just to make his brother smile again, even if only for a moment.</p><p><em>We could be happy together,</em> he thinks, as he deliberately misses his guess at Cluedo. <em>I would be here for you, always, and I would never leave you, and we could be happy, just the two of us against the rest of the world.</em></p>
            </blockquote>





	The Properties of a Binary System

**Author's Note:**

> This story is a companion piece to _The Boundaries of An Object Horizon_ , and while it's not strictly necessary to read that story beforehand, certain things will make a lot more sense with that context.
> 
> Again, people are not happy campers in this universe, though there is 100 percent less physical violence in this story. There are, however, lots of inappropriate feelings between blood relatives, so be forewarned.
> 
> Any personal correspondence is happily received at CaitlinFairchild1976@gmail.com.
> 
> Comments are the purest form of love, always.
> 
> Come follow me on Tumblr:  
>    
> [Caitlinisactuallyawritersname/a> Thank you so much for reading!](http://caitlinisactualllyawritersname.tumblr.com/)

The minor government official turns away from his coworkers, gazes out the window.

“Don’t be absurd,” Mycroft Holmes says to the glass, his demeanor blandly calm on the surface but pure ice underneath. “I am not given to outbursts of brotherly compassion. You know what happened to the other one.”

***

_Mycroft’s older brother was eighteen years old when William Sherlock Scott Holmes was born._

_One would think it was Mycroft, the seven-year-old middle child, who would resent the new arrival. Instead it was Sherrinford who loathed him on sight, although he was a grown man almost, and old enough to have known better._

 _Perhaps it was because Mycroft didn’t remember their father the way Sherrinford did. Their father had died when Mycroft was still a newborn; his life as an MI6 agent came to an abrupt and violent end as is so often the case in that line of work. Mycroft was barely a toddler when Timothy Holmes came into his life; he was a somewhat simple man, perhaps, compared to Miriam Vernet and her boys, but he was loving and kind, and much less likely to end up in a shallow Argentinian grave, and in the end he was only father Mycroft had ever known or wanted._

_Sherrinford, in contrast, had always resented their mother’s marriage, and as is so often true, his hostility extended to the newest sibling. It was fortunate that Sherrinford rarely came around, for he was relentlessly unkind toward William, dismissive at best towards his youngest brother and cruelly unkind at worst, shoving him aside, ignoring his chubby outstretched hands when they brought him a toy, sneering at him when he cried._

_When Billy was four and still mostly nonverbal, Mummy took him for his first developmental evaluation._

_“Course he’s an idiot,” said Sherrinford, lounging across a sofa, on one of his rare trips home from uni. “Just look at his father, for Christ’s sake.”_

_“Billy’s not an idiot,” twelve-year old Mycroft said hotly, defending his adored baby brother. “He’s just different. He likes certain things, and others upset him, that’s all.”_

_Sherrinford rolled his eyes and looked down at the little boy seated cross-legged on the floor. The small dark head bent in concentration over a full-color anatomy textbook._

_“Hey, William,” Sherrinford asked, contempt dripping from his voice, “Are you an idiot?”_

_Billy didn’t even look up. “Idiot,” he echoed absently, turning a page._

_“See, Myc,” Sherrinford said, chuckling nastily as he stood, “even the idiot thinks so.”_

_Sherrinford ambled out of the room as if hadn’t a care in the world, and Mycroft realized for the first time how much he hated his older brother._

_Soon after that encounter Sherrinford left England for good, going overseas for a diplomatic assignment. He never again returned to his mother’s home._

_Many years later, on a dark November evening, Sherrinford Vernet’s deep cover in the newly independent post-Soviet Ukraine was blown. Mycroft Holmes, the young rising star of MI6, was calm and composed as he looked at the intel, at the resources it would take to extract his older sibling, to bring him in from the cold._

_“Let him twist,” he said with a flat finality. “It’s not worth the risk.”_

_That was when the first whispers started about the bone-deep coldness of The Ice Man, the agent willing to sacrifice his own flesh and blood for the greater good of England. Shocked murmurs followed him down the halls as he passed. Mycroft felt no remorse, and slept well that night._

_It was far from the first or the greatest sacrifice Mycroft would make for his beloved baby brother._

***

Anthea slips soundlessly into the paneled meeting room, places a manila file folder in front of her boss, and disappears as silently as she arrived.

Mycroft brings the folder below table level, into his lap, and flips through the contents. His stomach sinks as he peruses the documents. He is disappointed, but not surprised, by the information in front of him..

“Excusez-moi, monsieurs et mesdames,” he murmurs, removing himself to the hallway.

He texts two words to Sherlock.

_**Jezebel confirmed. -MH** _

He waits a moment, pinching the bridge of his nose as an omen against the threatening headache. His text alert vibrates.

_**Understood. Require assistance. -SH** _

_**Must extract myself from meeting. 25 minutes. -MH** _

_**Too late by then. M is in play. -SH** _

_**I will try for 15. Will contact you ASAP. -MH** _

Mycroft is able to leave the meeting without causing irreparable harm to international relations seventeen minutes later and calls Sherlock but can’t reach him, sick panic beginning to bubble underneath his calm facade as he paces up and down the carpeted hallway. Five minutes later he slides into a low black car, phone pressed to his ear, Anthea behind him.

“Find them,” he hisses to the faceless minion at the other end of the line. “I don’t care what it takes. Find them, now.” He ends the call, pulling up every ounce of his willpower to not smash the phone into the bulletproof glass of the car window.

Anthea’s iPhone chirps. She presses a button, reads the message.

“Sir,” she says without inflection. “There’s been an incident.”

It’s too late and Mycroft knows it, by the time they arrive the burning warehouse is no more than smoldering debris. The three have already been transported to hospital, and as he will later learn, Mary has already begun to lose her daughter.

 _I was too late,_ he thinks. _I wasn’t there for him, I was too late, and I let him down. Again._

The pain in his heart is a rock, a mass of dark matter, infinitely heavy and black and cold.

***

_Mycroft went away to boarding school late, at age ten. Dad hadn’t wanted him to go, but Mum acquiesced to Mycroft’s wishes, knowing a public school background was crucial for the type of career her son envisioned for himself._

_He was always busy, so busy with clubs and meetings and even dreaded sport teams (Mycroft hates them all, wishes to work alone, but he always possessed an intuitive understanding about the importance of cultivating connections, of cultivating people, sowing crops to be harvested later at his leisure) that he seldom came home for more than a day or two at a time for more than a decade._

_He missed his little brother so much it was an ache, a physical pain, but sacrifices were necessary to ensure the future he wanted, and Mycroft was always nothing if not cold-blooded when it came to sacrifice._

_Upon later reflection, Mycroft sometimes wondered if the separation from Sherlock for all those important years was to blame, if somehow missing that crucial time, leaving a preschooler behind and coming back to a strange, almost unknown young man--maybe that time apart was what gave his twisted, unnatural love for his brother room to grow. Maybe if he had never left, he never would have come to see Sherlock so very differently._

_Or maybe he would have still, because Sherlock wasn’t even Sherlock until Mycroft was twenty-one._

_The summer after uni, Mycroft spent a rare extended break with his family. Newly arrived from the train station, he was putting his carefully folded shirts in the bureau drawer when his no-longer-little brother suddenly loomed in the doorway. William was fourteen, at the tail end of a particularly punishing growth spurt, six feet tall and seemingly made entirely of arms and legs. Overlong, wildly curling dark hair fell messily over his pale eyes, his face all cheekbones and lips and eyebrows, angles and planes where just months before he was still baby round._

_“Billy,” Mycroft said neutrally, Mum having warned him about the mood swings and tantrums, William’s normally difficult personality further inflamed by the storms of adolescence._

_“My name’s Sherlock,” his brother informed him, simultaneously lofty and sullen._

_Mycroft laughed despite his best intentions. “Oh, for goodness sake, why? William is a perfectly fine name.”_

_“Call me by my chosen name, or don’t speak to me at all,” his brother informed him coldly, and disappeared._

_Mum and Dad both thought it a passing whim, as did Mycroft, but Sherlock was always nothing if not eternally, hatefully stubborn, and utterly refused to respond to anything else, and by the end of the first week the entire family had given in, calling him by the name heretofore associated with a practically mummified ninety-year-old great uncle._

_Sherlock was so very, very different from the little brother Mycroft left behind. He had grown into a wild thing, leggy and weedy, by turns sullen and exuberant, affectionate and withdrawn, manically cheerful and miserably depressed. Exhausted by Sherlock’s neediness and temper, and more than a little afraid of him, his parents left him to his own devices; he spent most of his time hiding in the decrepit greenhouse at the rear of the garden, where he smoked cigarettes and listened to German death metal and conducted mad, self-created experiments late into the night._

_Mycroft found him completely fascinating, a feral, sharp-tongued creature, so different from the wide-eyed, worshipful little boy he once knew. Mycroft found himself hovering at the edge of Sherlock’s vision, hoping to tempt him closer, like a skittish alley cat, luring him with offerings of cigarettes and sweets, trying to reestablish the precious connection he had broken so thoughtlessly by leaving his brother behind._

_One warm, humid night Mycroft perched on the edge of a packing crate by the greenhouse door, watching his brother work. “Stay or go,” Sherlock said indifferently over his shoulder, “no difference to me.” Rammstein blasted into the soft summer evening as his little brother hunched over his microscope, shirtless, his naked back so achingly pale and vulnerable._

_And Mycroft, the man who had been far, far too busy becoming someone important to ever look at another person with amorous intent, realized with a sudden, bottomless horror that he desperately wanted to touch Sherlock, run his fingers over his sharp shoulder blades and taste the salt of his alabaster skin and press kisses into the back of his neck in a manner that was a million miles away from anything brotherly or right._

_He fled in terror, running away without a word from the tumbledown greenhouse to the sanctuary of his dark, dusty-smelling childhood room. There he laid awake, tormented by shame and self-loathing and a persistent, hateful erection that absolutely refused to subside. He fought his traitorous body’s demands, refusing to touch himself, tossing and turning until at last he fell into a thin, troubled sleep._

_Mycroft dreamed of the sharp angles of his brother’s body, of dark curls tumbling into silver eyes, of moonlight pale skin under his exploring fingertips._

_The next morning, Mycroft invented a social obligation in London and left without a word of goodbye to Sherlock._

***

Mycroft hovers in the doorway of the hospital waiting area. His brother sits alone on the cheap, ugly couch, drawn and sallow under the fluorescent lighting.

“The baby’s dead,” Sherlock says without preamble, voice utterly devoid of inflection.

“Sherlock,” Mycroft says. “I should have found out sooner. I should have left that meeting. I--”

“Stop it,” Sherlock hisses. “Christ, Mycroft, just stop. You’ve never let anything fall on my shoulders, you’ve protected me my entire life, you’ve babied me, and I need to feel this. This is my fault, this is my failure, and I need to feel it, so. Just. Stop.”

“Sherlock,” Mycroft says. “Tell me what you need.”

“I need you to leave me alone,” Sherlock says, and buries his face in his hands. His shoulders hitch in what might be a silent sob, and Mycroft is seized by the desire to drop to his knees and wrap his arms around his brother, to kiss him and soothe him and breathe him in. He holds perfectly still until the impulse passes, leaving him carved out and hollow in its wake.

“As you wish, brother,” he says with a practiced calmness he doesn’t feel, and retreats, even though it kills him to leave Sherlock like this.

Mycroft goes from the hospital directly to 221B, where he conducts a sweep of all Sherlock’s hiding spots; he can’t keep Sherlock from using if he’s dead set on it, but he can at least throw up enough of a buffer zone for Sherlock to reconsider his worst impulses.

He very deliberately straightens the front door knocker as he leaves.

***

_Above and beyond the knowledge that it was utterly illegal and horribly addictive, the main problem with heroin was how it made Sherlock so very tactile and affectionate, how it stripped away the cloak of aloof coldness he wrapped himself in when sober._

_At twenty-four, Sherlock’s drug problem had not yet hit rock bottom, but the downward trend was all too apparent. After dealing with his brother's first two brushes with the law, and afraid that Sherlock will run out of money and resort to unsavoury means of maintaining his habit (the thought of someone using Sherlock’s body in trade makes a terrifying black rage swell in Mycroft, a homicidal fury truly frightening in its intensity), Mycroft brought him to stay at his house in Pall Mall._

_It’s an exercise in utter futility to try to keep Sherlock under lock and key; he outsmarted every monitoring system devised without even seeming to try, walking out whenever he pleased, doing God knows what, God knows where until the small hours of the morning. One late night, as winter moved tentatively towards spring, Sherlock opened the door to Mycroft’s room and slipped into his bed wearing nothing but pants, wrapping his arms and legs around Mycroft like a warm, opiate-dependent octopus, smelling of Dunhills and seedy alleys and something else underneath, the smell of Sherlock himself, cedarwood and oranges and musk, and it made Mycroft’s amygdala light up like fireworks over London Bridge._

_Mycroft held himself very, very still as Sherlock burrowed his nose into the joint where Mycroft’s neck met his shoulder._

_“You’re so skinny now,” Sherlock sighed. “You were nicer to cuddle when you were fat.”_

_“Sherlock,” Mycroft said neutrally, not even knowing what words the rest of that sentence could possibly contain._

_“You don’t love me anymore. Why don’t you love me anymore, Myc?” Sherlock asked him, his plaintive voice making him sound almost like the child he was not so long ago, and it felt like a knife straight to Mycroft’s heart._

_“I care about you very much, Sherlock,” Mycroft says. “Come on, you know that.”_

_“You don’t smile at me anymore, and you flinch when I get too close,” Sherlock said sadly. “You only maintain eye contact for less than three seconds, and you generally leave a room less than five minutes after I enter it. The obvious deduction is, you don’t love me anymore.”_

Oh, brother mine, _Mycroft thought._ You see, but you do not observe. __

_“That’s not true, Sherlock. We’re adults now, and it’s different. There are limits to affection between two grown siblings.”_

_“I don’t care. You shouldn’t care.” Sherlock began mouthing at his neck, sloppy, without finesse, clearly inexperienced but obvious in intent._

_Sherlock was under the influence, not in his right mind. Taking what was on offer was the one thing that Mycroft knew would make this entire horrible situation even worse than it already was._

_It took a degree of self-control Mycroft didn’t even know he possessed not to turn around and crush Sherlock’s mouth under his own, not to touch him and stroke him, not to take what his intoxicated brother was so heedlessly offering._

_“Sherlock,” Mycroft said, intending it to come out stern, but instead his voice sounded breathy, uncertain. “Sherlock, stop that. You are very, very high right now and you will absolutely regret your behaviour in the morning.”_

_Sherlock huffed out an unhappy noise, but took his mouth away from Mycroft’s skin, leaving him simultaneously relieved and bereft. Mycroft allowed himself the tiny concession of taking one of Sherlock’s hands and holding it between his own, purely as a comfort to his brother._

_“I do love you, Sherlock,” Mycroft said quietly, soothingly. “More than you’ll ever know. Go to sleep, now.”_

_“We could be happy together,” Sherlock mumbled into his shoulder, as Mycroft struggled to keep his breathing even. “We could.”_

_Sherlock fell asleep minutes after, and Mycroft extricated himself from his brother’s cephalopodic embrace and fled to the guest bedroom at the end of the hall. He locked himself into the ensuite, stripped off his night clothes, and stepped into the hot spray of the shower, revolted by the achingly hard cock that was proof of how badly he wanted to do terrible things to his own sibling._

_He would never, ever cross that line, not even if Sherlock asked (and he had been asking, earlier, in his clumsy, addled way. Mycroft knew that.) Not even if Sherlock begged. He could never, ever forgive himself if he touched his baby brother like that. But his traitorous body could not be so easily mastered, and for the very first time Mycroft gave in and touched himself to thoughts of Sherlock._

_He called up long-repressed fantasies, stroking himself as he imagined Sherlock on his knees in front of him, his gorgeous lips stretched around his cock as he sucked. Mycroft moaned out loud as he gripped himself harder, imagining the wet heat of his brother’s mouth, his tongue against the underside of his shaft as Mycroft wove his fingers through dark curls, guiding his movements, watching him move up and down along his hard length, watching his own brother take him willingly down his throat. In his imagination, Mycroft fucked Sherlock’s mouth, feeling his balls tightening, the pleasure a hot coiling itch in his spine, he was going to come in Sherlock’s mouth and he would swallow it all, every last drop--_

_“Fuck, yes, Sherlock,” Mycroft gasped as he came, hard, harder than he ever had in his life, riding a sharp hot crest of pleasure, thick white spurts sliding down the shower tile as he spasmed over and over against his own hand._

_Mycroft braced himself against the shower wall, breathless, as the wave ebbed all too quickly and the horror of what he had just done filled him with shame, leaving him with a sickly, nauseated chill. He sluiced water over the tile, washing away the evidence of his foul thoughts, and soaped and rinsed quickly, shutting off the taps and drying himself perfunctorily before redressing in his pajamas and turning down the sheets in the guest bed._

__I will never, ever do that again, _Mycroft swore to himself._ I will never think of Sherlock like that again. _He was certain his visceral, burning self-hatred would keep him awake, but the biological realities of a resounding orgasm soon caught up with him and he fell soundly asleep._

_The next morning, Mycroft left for work at a punishingly early hour, and when he came home Sherlock was still in his dressing gown, laying flat on his back on the porch, smoking a cigarette and ignoring Mycroft’s greeting. If Sherlock remembered any of his actions the night before, he didn’t mention it._

_“I’ve had all new electronic locks installed,” Mycroft announced. Sherlock continued to ignore him. Mycroft shrugged and left him to whatever it was he was contemplating. It didn’t matter anyway. There was no way to keep Sherlock in if he didn’t wish to be confined._

_Mycroft ate a small, unsatisfying vegan dinner and went to bed early, steadfastly thinking about absolutely nothing whatsoever._

_Sherlock was gone the next morning, his room blank and empty. Two years would pass before Mycroft would see his brother again._

_Faced with the loneliness of a house grown still and empty without Sherlock’s chaos to fill the corners, Mycroft’s resolve soon crumbled and before forty-eight hours had passed he succumbed to thoughts of Sherlock again, this time imagining him naked and spread as Mycroft went down on him, his brother’s imagined cries of pleasure filling his ears as he came, spurting warm over his own hand in the dark._

***

Mycroft is dealing with a difficult situation regarding an Uzbek terror cell when the intercom chimes, breaking his concentration. He sighs in annoyance and thumbs the button. “I told you I was not to be disturbed,” he says, not bothering to hide his irritation.

“It’s DI Lestrade, sir,” Anthea informs him. “Regarding Mr Holmes.”

Mycroft exhales. “Right, then. Send him in.”

The door opens, and Gregory enters. Mycroft notices immediately the tightness around the man’s eyes, evidence of Lestrade’s clear concern for Sherlock’s well-being. Whatever it is, it is something Mycroft should have been paying closer attention to, something he should have addressed before it got to the point where Lestrade felt the need to bring it to him. Guilt roils in Mycroft’s belly.

“What can I do for you, Detective?” he asks smoothly, burying the sick feeling in his stomach, letting nothing show, freezing his worry under layers of ice. 

“Sherlock showed up high to a crime scene last night,” Lestrade states bluntly. “Half out of his mind on coke, pupils like pinpricks and looking like someone’s been using his face for a punching bag.” The detective steps closer, glaring at Mycroft accusingly. “I thought you said you were keeping an eye on him, Mycroft.”

“I do have other responsibilities, Detective, as you well know,” Mycroft answers smoothly. “What are your impressions, then, about his activities?”

“With the way his face looks, my first thought is that he’s gotten back into street fighting,” offers Lestrade. “I know John hasn’t been around for awhile and since...everything that happened, maybe Sherlock’s fallen back into more than one of his old habits. I just...I told him to not show up at a crime scene until he’s clean. I don’t know what else to do. Maybe before everything went to hell I could have sat him down, talked to him. But lately? He’s just, he’s untouchable right now. Completely closed off again. So, I’m telling you instead.”

Mycroft takes a deep, calming breath, and gives Lestrade his second-least-creepy fake smile. “I appreciate it, Gregory. I assure you I will look into it immediately.”

“Well, that’s good, then.” Lestrade shifts his weight, looking uncomfortable. “Your brother’s a right bastard most of the time, but at the end of the day he’s a friend, and I just...see that he doesn’t get hurt, yeah?”

“Of course.” Mycroft thumbs the intercom, and a moment later his office door opens, Anthea gliding smoothly in. “I truly appreciate your assistance. Anthea, would you please see DI Lestrade out?”

The door clicks shut behind the pair, and after a long moment of consideration Mycroft opens his laptop and pulls up an encrypted feed.

Sherlock had known about the surveillance installed in the flat, a precaution against the unknown dangers of Moriarty’s return; with the man’s actual death Mycroft had all of the cameras and audio equipment removed. All of them except one, hidden away where even Sherlock had failed to find it.

Mycroft knows he is betraying his brother’s trust; he and had sworn to himself that it was just in case of true emergency, that he would respect his brother’s privacy unless a situation grew dire.

Certainly, a return to cocaine and underground fight clubs counts as dire, he tells himself as he opens the first file.

Mycroft tabs through the hours of footage, expecting to find evidence of Sherlock using, either pulling out his precious box or snorting. He is honestly, truthfully blindsided by the images of Sherlock and John hitting each other, snarled obscenities captured clearly over the audio feed.

He is poleaxed by the sight of his brother over the arm of the sofa, John Watson fucking him halfway into next week.

 _Turn this off NOW,_ he tells himself. _You have the information you need. Delete all these files, smash your computer, douse it in petrol, burn the entire building down if you have to but for the love of God please, please don’t watch any more of this._

Instead he gets up, crosses the room, locks the door, and returns to his desk chair. He watches all of it, transfixed, unable to turn away, watches his brother, the love of his heart, engaging both in brutal, bloody violence and loud, filthy intercourse, every one of Mycroft’s most shameful fantasies brought to life in color and sound. Sherlock on his knees, fingers roughly twisted in his dark curls, gagging and drooling as his lips stretch around John’s hard cock. Sherlock whimpering as John fingers him open, calling him filthy names as Sherlock wraps his hand around himself and pleads with John to let him come. Sherlock on his elbows and knees, arse in the air, begging to be fucked. John pounding viciously into Sherlock’s body, tearing obscene cries and moans from Sherlock’s throat, making him scream, making him shudder as comes, spilling onto the faded sitting room rug.

Uzbekistan completely forgotten, Mycroft watches it all, rapt and horrified and incredibly, shamefully aroused. Mycroft is left shaking and ill, and rock hard against the zip of his trousers, using every ounce of willpower not to touch himself, not to get himself off to images of his own brother being willingly beaten and fucked into oblivion.

He feels nauseated. He feels incandescently angry. He is also painfully aroused, his whole being unable to think beyond the hot, insistent ache in his groin.

 _My brother,_ Mycroft thinks for the hundred thousandth time. _My own little brother. Christ. I’m a monster._

He doesn’t touch himself. Instead, he places a discreet phone call from his encrypted line, a call to a trusted business associate he engages very occasionally, when he is too overwhelmed to cope in any other manner.

Mycroft takes a car home to Pall Mall, sends his staff home for the night, and takes a long, hot shower. Forty-five minutes later, there is a knock on his door.

The young man sent over by his associate shares superficial similarities with the rest of them; pale, lean, long of limb, dark of hair. As ever, it's not even close to enough; he feels wrong, smells wrong, his eyes are muddy slate instead of pale starlight. His fingers are too practiced, his sighs and moans too obviously faked. 

Mycroft is courteous and polite and pays him well, and makes him leave immediately after. 

With a clearer mind, he goes back to the international crisis he has been neglecting, and buries his shameful, unnatural desires under another layer of ice.

***

_After Sherlock hit rock-bottom, ODing and almost dying on the grungy kitchen floor of his Montague Street flat, Mycroft used the considerable resources at his disposal to enlist Detective Lestrade’s help. He cleared the way for his promotion to DI, and in exchange procured the man's agreement to allow Sherlock access to the Yard, to the criminal cases he loves more than drugs, predicated on the condition that he gets and stays clean._

_Detective work proved to be the key to keeping Sherlock off drugs, and this last time, miracle of miracles, he stayed clean. Sherlock pretended he didn’t know that Lestrade is on Mycroft’s speed dial, and Mycroft pretended he didn’t know that Sherlock knew._

_The two brothers drifted into an uneasy detente. They needed each other to function, after all, in ways both stated and desperately unspoken._

_Mycroft knew he would never, could never have Sherlock for himself in the way he truly wanted, but he consoled himself with the selfish thought that he would always be the most important person in Sherlock’s life. Sherlock was not a sociopath, he had never been a sociopath, but he only fell short of an autism spectrum diagnosis by bare inches and he was never good with people and Mycroft selfishly told himself he was the only one who would ever even want to deal with Sherlock, that his brother would never be able to find anyone else who could put up with his odd, offputting personality._

_Then an unassuming Army doctor in a fuzzy jumper showed up one day, and somehow walked directly into the armed fortress that was Sherlock’s heart. And Mycroft, the man who saw everything, observed everything, soon realized he had severely underestimated the interior landscape of the little brother he thought he knew so well._

***

Mycroft is planning his intervention when Doctor Watson saves him the trouble by showing up unannounced. John is waiting in his office, standing at parade rest, the military stiffness of his posture belied by the exhaustion in his face, the sallowness of his skin, the grief in his eyes. 

Acclimated to cool, calculating distance, the red haze of rage that fills Mycoft’s mind takes him by complete surprise.

 _l will kill you with my bare hands,_ Mycroft thinks, and has to forcibly restrain himself from baring his teeth and growling at the man who is hurting Sherlock.

Mycroft breathes in, breathes out, finds the calmness he needs to function. “Doctor Watson,” he says in his most carefully civil tones, using the greeting to buy the time necessary to figure out how to best dispose of the man’s soon-to-be lifeless body.

“Mycroft. I need…” John stops, rubs the back of his neck, his classic anxiety tell. “I need your help. I’m in a-- well, Sherlock and I, we’re in a--”

Mycroft holds up a hand. “I am aware of your situation in regards to my brother. What I don’t know is what you possibly think you can ask me for, other than a relatively painless death.”

John’s look turns to one of indignation shading into horror. “You are aware. You’ve been spying on us, then. Do you know how fucking creepy that is, Mycroft?”

“Here you are, asking me for help because of what you’ve done to him, and you dare judge me?” Mycroft laughs, a hollow, terrible sound that grates on his own ears.

The fight goes out of John at that; the man sags visibly under the weight of his guilt. “I know what it looks like,” he says quietly.

Mycroft draws himself up to his fullest height and pins him down with his icy fury. “Looks like?” he echoes incredulously. “Believe me, I know exactly what it _is_. You have used and abused and hurt the most extraordinary, sensitive, and brilliant man I have ever known, taken him and broken him like a thoughtless, greedy child breaks a toy. You have broken the heart of the only person I love in this world; so help me understand, _Doctor,_ why I shouldn’t send you directly to hell this very moment.”

John’s eyes widen but his voice remains calm. “Because if you send me to hell, Mycroft, he will follow me there. You may think I don’t love him--you’re wrong, by the way, but I can’t fault you for it--but I do, and I don’t want to know what he would do if I were dead. Neither do you, I don’t think.”

Mycroft exhales, knowing the truth of John’s words. “Then what is it that you want?”

John runs his hands through his disheveled hair. “I have to leave. I don’t want to, but I need to stop this before we hurt each other any more.” He looks up, then, into Mycroft’s face, his blue eyes sorrowful but unafraid. “If you really plan to kill me, I won’t stop you. I won’t even blame you. But think of Sherlock, please, Mycroft. I don’t want to hurt him anymore, and I know you don’t either. So how about you help me instead.”

Mycroft considers the shorter man for a long moment, then goes his desk, opens a tab on his laptop. “Doctors Without Borders. They are in desperately need of staff in Yemen. I can arrange for you to leave by tomorrow evening. “ He wrote a number down on a sheet of notepaper and handed it to John. “Dr Nadal. Call him this afternoon. Do you have a solicitor?"

John nods.

“Give him my number. I’ll deal with your belongings--disposition or storage, your choice.”

John nods again.

“Is there anything else you need then, Doctor?” Mycroft asks with icy finality.

“If I write a letter to Sherlock, saying goodbye...will you make sure he gets it?”

Mycroft purses his lips. “Yes.”

“Promise me,” John says.

“You are in no position to ask me for anything, Doctor, but yes, I promise that I will deliver it to Sherlock myself.”

“I guess that covers it, then,” John says, and suddenly he looks small and exhausted and far older than his forty-four years. He shakes his head a bit, as if clearing his thoughts. “Thank you, Mycroft. For what it’s worth--” he pauses, choosing his words with care--“there’s no way you could hate me more than I hate myself right now.”

“Oh, Doctor Watson,” says Mycroft, sadly. “Believe me when I say that is not even remotely true.”

***

_The two years after Sherlock’s fall were, in some ways, the best years of Mycroft’s life._

_He and Sherlock spent hours together, scheming, plotting the takedown of Moriarty’s network. Sherlock texted him, called him, three, four five times a day. Mycroft answered every single time, no matter the hour, no matter the demands of his work. He went to visit him in safe houses in Helsinki, in Hamburg, in Budapest, making sure with his own two eyes that his brother was safe, examining his injuries, watching over him as he slept._

_They grew close again, as close as they were as children, once again each other’s only touchpoint in a sea of indifferent, idiotic humanity._

_Sherlock never mentioned the army doctor, not once in all that time. Mycroft was foolish enough to think that meant something, foolish enough to forget that Sherlock stored the greatest treasures of his heart in his darkest, most secret places._

_They could be enough for each other, Mycroft reflected in his most private moments. Even if they can never be what Mycroft wishes for in the deepest recesses of his heart, they could still be everything to each other._

_They could be happy together. They could._

_In Serbia, Mycroft calmly looked at the man who ordered Sherlock tortured, listened to him plead for his worthless life, then shot him point-blank between the eyes._

_Mycroft held his shaking, bleeding brother in the back of an unmarked black van as it sped toward the Hungarian border, stroking his matted hair, shushing him with nonsense words of affection as if he were again a small, helpless child. Selfishly, greedily, Mycroft reveled in his brother’s need for him, for contact, for comfort._

_“You were enjoying it,” Sherlock would say later, voice dripping with disdain, but there’s also something else there, an emotion he can’t quite parse and Mycroft, sick with shame, would know exactly what he meant._

_It was true. He had._

***

Sherlock finds the camera before Mycroft can have it removed. He brings the mangled innards to Mycroft’s office, drops them on his desk, his face stony.

“It was from the Moriarty surveillance,” Mycroft begins, “and after, I was concerned about the possibility of relapse--”

“Enjoyed the show, then?” Sherlock says, his voice terrifyingly devoid of emotion.

“I erased the files,” Mycroft says smoothly. “And then I scrubbed my skin raw with a wire brush, and soaked my brain in bleach for a solid week.”

Mycroft is certain of his calm demeanor in front of any other person on earth, but this is Sherlock, the one person who can see through him in an instant. Sherlock looks at him for a long moment, and Mycroft sees his brother do something he’s never seen before: Sherlock skates up to the very edge of a deduction, contemplates, and makes a deliberate decision not to know whatever he sees there. His silver-blue eyes go blank.

“Of course,” Sherlock murmurs, his face smoothly unreadable, a million miles away from Mycroft. He turns and leaves without another word.

That night, Mycroft works until the evening rounds the corner to morning, desperate to keep his brain and hands occupied, but the universe as usual, conspires against him; no wars to start, no international incidents to resolve, not even a single captured spy to negotiate over, and in the small hours of the night he finds himself seated in front of the fireplace of his study, scotch in hand. He deleted the files from the network, but he remembers everything, remembers every dark, desperate, private moment, remembers every single thing he should never have known about his own brother. In his mind’s eye he sees the image of Sherlock’s long, pale body on all fours, the muscles of his back, the curve of his hip. He hears the sound of his voice as he begged to be taken, filled, fucked harder. How he sounded as he cried out his release, shuddering as orgasm wracked his body.

Mycroft used to resolve he would never think about Sherlock in that way again, but age and cynicism have made him a realist in the end. He sets his tumbler down on the side table and opens the fly of his trousers, wrapping his hand around his painfully hard erection and stroking, pulling firmly, rubbing his thumb over the tip.

He closes his eyes and imagines what it would feel like to fuck his brother. 

_Please, Mycroft,_ Sherlock’s voice whispers brokenly in his ear. _Please. Make me feel good. Make me come, I want to come for you. Please._

His disgust with himself is enormous, pervasive, but the pleasure of imagining the feel of Sherlock’s body, the hot tight pull of him, is greater by orders of magnitude. It almost feels worth it.

Until after he climaxes, and then he just feels sick and cold and alone.

***

Billy Holmes was his adored baby brother, the toddler who clung to him as a child, the round- faced preschooler who brought him tadpoles and and earthworms, the little boy who curled up in his bed as Mycroft read him stories of the high seas, dashing tales of pirate adventure.

Sherlock Holmes is the man Mycroft is in love with, the man he dreams of at night, the man he desires with every atom of his body and soul.

On bad nights, that razor thin edge of semantic distinction is all that keeps Mycroft from opening his veins in a warm bath.

***

_“I’m not lonely, Sherlock.”_

_“How would you know?”_

***

Despite being the entirety of the British government, Mycroft always keeps his schedule open on January 6. Just in case.

This year his phone rings. It’s Sherlock’s fortieth, and Mycroft goes to Baker Street and eats a piece of cake just to give Sherlock some ammunition, something to tease and insult him over. Something to make his brother smile again, even if only for a moment.

 _We could be happy together,_ he thinks, as he deliberately misses his guess at Cluedo. _I would be here for you, always, and I would never leave you, and we could be happy, just the two of us against the rest of the world._

Mycroft drops his hand briefly on Sherlock’s shoulder as he takes his leave, feeling the warm muscle under expensive Egyptian cotton, and for once in his life Sherlock doesn’t flinch or shrug off his brother’s fleeting touch.

***

_Mycroft knew there would be something in the punch; he hadn’t expected it to be quite so strong._

_“Also, your loss would break my heart,” he heard himself say, with a dim but growing horror as the words tumbled, unbidden, out of his mouth. The punch. Jesus. What in the bloody hell had that junkie spiked it with?_

_Sherlock choked on his cigarette. A look of panic crossed his face, gone the next instant._

_“What the hell am I supposed to say to that?” Sherlock sputtered, and Mycroft felt a terrifying, overwhelming impulse to lay his heart out for his brother to see._

_No. He would never do that, would he, because this is not Sherlock’s burden. It is his, and his alone to bear. With great effort he pulled himself together._

_“Merry Christmas,” Mycroft said instead, a thin, odd-feeling smile pasted on his face._

_“You hate Christmas,” Sherlock noted with a snort of amusement._

_“Perhaps there was something in the punch.”_ Don’t get yourself killed before I can rescue you. I love you. Be careful. _Mycroft managed to keep these mortifying sentiments off his lips, but only just._

_“Clearly. Go and have some more,” Sherlock said, the only acknowledgment of his awareness of Mycroft’s complicity in this mad, foolish scheme._

_Mycroft crushed out his cigarette and returned to the house, numbness spreading through his limbs._

_(He didn’t know what Wiggins put in the punch, but the man was_ wasted _as a homeless drug addict. Mycroft made a mental note to present him with a better offer, after.)_

***

Mycroft learns of John’s return as soon as he clears Customs. He goes to visit Sherlock two days later.

Confounding twenty-five years of expectations, Sherlock makes both tea and small talk. He never mentions John. It isn't necessary. Although he is not physically present, John Watson envelops Sherlock, suffuses him. In the face of his brother's joy, Mycroft can't bring himself to voice the words of warning he came to deliver.

Sherlock is alive again, glowing, lit from within. His heart is whole once more, and Mycroft finally understands how desperately he has underestimated Sherlock’s capacity for love.

Mycroft leaves Baker Street, and waves off the car waiting for him. Anthea rolls down the window, her normally inscrutable face creased with concern.

“Sir?”

“I’m in some need of fresh air. Follow along if you must, but I fancy a walk back to the office.”

“As you wish, sir.” Anthea’s face smooths out into her usual bemused neutrality. The window rolls back up, leaving Mycroft with a simulacrum of solitude.

Mycroft walks, exploring the dimensions of his new awareness of Sherlock, coming to realize the fundamental truth he has willfully ignored for far too long: Sherlock is not his to keep. Sherlock had never been his, no matter how much Mycroft tried to protect and insulate and control him. Mycroft sees with sudden clarity how transparent he had truly been all these years, how large he had writ his obsessive love for his brother in every surveillance camera, every cctv feed, every elaborate plan he had carried out in the name of saving Sherlock from himself.

All these years, Mycroft has been trying to claim Sherlock as his own, in the most stupid, cringing, obvious-in-retrospect manner possible.

Sherlock is a grown man now, forty years old, and most important of all, Sherlock is not Mycroft’s to keep. 

Sherlock’s heart belongs utterly to John Watson, who may be a borderline-abusive danger junkie with an anger problem, but possesses the undeniable moral high ground of, well, of not being Sherlock’s biological sibling.

Here is the stark, final truth: Mycroft has to give up his selfish idea that he is the only person willing and able to care for Sherlock Holmes. He will never fully believe John Watson is a good enough man for his brother. But Mycroft sees, now, that it isn’t his decision to make.

This is the task, then, laid out before him, the one thing the smartest man in England has no idea how to do.

He has let his brother go.

It is a long, chilly walk to Downing Street. Halfway there it begins to rain, and for once in his life Mycroft Holmes faces the elements unprotected.

***

_The chemistry is incredibly simple and very destructive._

_Mycroft watched the love of his of deepest heart shoot Charles Augustus Magnussen in cold blood. He watched Sherlock sacrifice everything, give up his freedom, give up his very life to protect the heart of the man he loves in turn._

_“Oh, Sherlock,” he whispered. “What have you done.”_

***

All of John Watson’s financial transactions are routinely monitored by a minor office of the British government.

Which is how Mycroft Holmes knows the man just spent fifteen hundred pounds at a very upscale jeweler just off Oxford Street.

Mycroft is waiting in the darkened sitting room when John returns home after his long workday.

“Two platinum bands, brushed finish. Costly yet tasteful. You must be _very_ certain of your reception, Doctor.”

“What I am certain of,” says John as he puts the shopping down on the kitchen table and fills the kettle, “Is that none of it is your fucking business.”

Mycroft says nothing, just sits in Sherlock’s chair and bides his time until the kettle boils. John brings him a mug of tea (he may be pissed off, but he’s still British, after all) and sits in his own chair opposite.

“I’m sure you understand, Doctor, how the phrase ‘til death do us part’ applied to you and Sherlock does not suffuse me with the warmest of fuzzies,” Mycroft notes dryly.

“I do understand,” John says quietly, and some of the hardness leaves his voice. “I do, Mycroft.” John takes a sip of his tea. “I know I didn’t treat him well. We--well, we didn’t treat each other well. But it’s been over a year now that I’ve been back, and we’ve forgiven each other, and I really want us to start a new chapter in our lives. I hope you can respect that, at least.”

Mycroft takes a sip of his own tea, suddenly uncertain what to say next. “I’ve spent my entire life keeping him safe,” he begins. “He’s my--he’s my brother,” he finishes, lamely, finding himself caught between what he desperately wants to say and the need to keep his innermost feelings protected.

John looks at him speculatively, takes another sip of tea, and puts his mug aside. “I think,” he says quietly, “we have a lot more common ground than it may at first appear.”

 _Oh God. Oh God._ Mycroft puts on his chilliest demeanor as armor. “I’m certain I have no idea what you mean.”

“I spent six years telling everyone who would listen that I’m not gay,” John says, “and I’m not. I’m still not, but here I am, planning to ask your brother to marry me.” He smiles then, and it’s a gentle smile, full of understanding, and it fills Mycroft with black curling tendrils of self-hate. “Sherlock has a way of getting past people’s defenses, doesn’t he? Turning everything upside down and inside out. He’s a force of nature unlike any other, he’s like no one else in this world, and he just has a way of...drawing you in. Despite yourself. Doesn’t he?”

Mycroft realizes with a sickening thud that John knows. This ordinary, spectacularly unobservant man has likely known since that last conversation, before he went to Yemen. Mycroft’s mouth is dry, his pulse racing.

He has nothing left to offer except the truth.

“You must think me a monster,” Mycroft says into his tea, forcing the words out, his voice barely above a whisper.

John shrugs, but doesn’t drop his gaze. “I don’t. I think he’s the only person you love in the entire world, and he has a way of making sane people go crazy.” He chuckles a bit. “I might be the only other person in the universe who could possibly understand.”

“I’ve never--I would never--” Mycroft begins, and John holds up his hand, shakes his head.

“I know that. I do. I know you are a lot of things, a lot of them not good, but I know you wouldn’t do that.”

Mycroft exhales, relieved. Then another horrifying thought occurs to him. “Does he...does he know, do you think?”

John raises an eyebrow. “I was going to ask you the same thing,”

“I think…” Mycroft struggles, uncharacteristically, for the right words. “I think he decided, once, to not make the deduction. A pre-emptive deletion, if you will.” He swallows down something thick and heavy in his chest. “He must never, ever know, Doctor Watson. This is my burden to bear, not his. Never his.”

“Of course,” says John, and his eyes are kind, far kinder than Mycroft deserves. “I am sorry. It must be awful. And for what it's worth, I don’t think less of you.”

“Thank you, Doctor.”

“Do you think, maybe, you could find it in you to call me John again? It would mean the world to me.”

The man has offered him forgiveness for the unforgivable. Mycroft feels like something heavy and black has been lifted off him, if even just fractionally, and finds himself happy to offer forgiveness in return.

“Of course. Thank you, John. And if it’s all the same to you, I’d prefer never, ever to revisit this topic of conversation again.”

***

_“Don’t be absurd,” Mycroft Holmes said to the window, blandly calm on the surface but pure ice underneath. “I am not given to outbursts of brotherly compassion. You know what happened to the other one.”_

_What the men and women in that room didn’t know, could never know, is that everything Mycroft has ever achieved, everything he has ever accomplished, everything he has ever sacrificed, has all been done for the love of Sherlock Holmes._

***

Sherlock is pacing the confines of the waiting area, just outside the small ceremony room of the Guildford Registrar’s office where the few guests are assembled. He is managing to contain his bubbling anxiety, but it is a near thing and it’s making Mycroft anxious as well by sheer proximity.

John is running late, and Sherlock is quietly freaking out.

“He’s late, Mycroft. He’s never late, he’s the responsible one. I’m the one who is late for things, not him, so why is he not here?”

“Gregory just called, there was an accident on the A3, they will be here in a few moments. For goodness' sake, Sherlock,” Mycroft puts a hand on Sherlock’s elbow to forcibly stop the pacing, “You’re making yourself all rumpled.” He smoothes down the hair that Sherlock has mussed into a madman’s halo by his nervous ruffling and pulling, adjusts his lapels, fixes his tie. “You’d think it was the most important day of your life by the way you’re behaving,” Mycroft teases gently.

Sherlock neither confirms nor denies the statement. “And he’s making me wear a tie,” he grouses. ”Why do weddings have to involve slow strangulation? Is it some kind of metaphor?”

“You look dashing,” Mycroft says soothingly.

“What the hell is wrong with you?” Sherlock snaps. “What the hell is wrong with all of you?” He winds his long fingers back into his hair, undoing all of Mycroft’s previous work. “What the hell is wrong with me?” he asks his brother as he leans against the mahogany paneling and bangs his head against it, gently, just the once.

“You’re nervous. Understandably so.” Mycroft raises an eyebrow. “After all, I don’t think either one of us ever thought you’d find yourself in this scenario.”

Sherlock stops, exhales. “True,” he admits. “This is, as everyone knows, so not my area. Sentiment is something I delegate to John, who is now--” he checks his watch--”six full minutes late.”

Mycroft is opening his mouth to say something uncharacteristically reassuring when a silver car turns into the gravel drive. He sees the worry and anxiety disappear instantly from his brother’s face, replaced by a pure, beaming joy that both warms and wounds Mycroft’s heart.

“You love him, don’t you,” Mycroft says quietly. It’s not really a question.

“Of course I do,” Sherlock snaps, only it comes out much fonder and less brittle than he intends. “I wouldn't go through this ridiculous, antiquated ritual if I didn’t.”

Mycroft completely surprises himself by surging forward and pulling his brother into a rough, awkward hug. Sherlock stiffens in shock, then relaxes into it, returns it, wrapping his arms around his brother’s back.

“Be happy, Sherlock,” Mycroft murmurs against his ear, trying to put everything he wants for his brother into those few simple words. “Please, just...be happy.”

Sherlock huffs out a soundless laugh and squeezes him, once. “I am, Myc,” he whispers back. “I am.”

John and Lestrade walk through the open front door. Lestrade looks a bit taken aback at the brothers’ embrace but John just smiles, indulgent and fond.

Mycroft Holmes takes a deep breath and does one last thing for his beloved baby brother.

He lets him go.

Mycroft steps back, looks at Sherlock, and smiles, gesturing to the door of the ceremony room. “After you, brother mine.”

Sherlock grins, almost shy, and grabs John’s hand, his eagerness putting lie to his earlier complaints about antiquated rituals. Lestrade follows them, and Mycroft straightens his back, squares his shoulders.

A final sacrifice, then, for the love of Sherlock Holmes.

Mycroft walks into the room where his brother is about to be married, and closes the door behind him with a solid, muffled thump.

 

_~fin~_

**Works inspired by this one:**

  * [The Properties of a Binary System [PODFIC]](https://archiveofourown.org/works/6176443) by [Lockedinjohnlock](https://archiveofourown.org/users/Lockedinjohnlock/pseuds/Lockedinjohnlock)




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